The invention relates to an automatic machine for folding flat die-cuts into tubular shape, and in particular, die-cuts with pre-creased fold or hinge lines serving to mark out the sides and securing flaps of a box type container.
The prior art embraces various machines by which box die-cuts can be folded into a tubular shape; the flat forms are punched from rigid material and provided at least with creases separating a number of adjacent parallel side panels, and a securing flap parallel to the side panels.
Die-cuts are stacked generally in a magazine loader and removed one by one from the base of the stack. Removal is effected in most instances by suction means that latch onto one side panel of the die-cut and are then traversed through an opening shaped in such a way as constrains the rigid material to fold along the two longitudinal creases which flank the side panel engaged by the suction means.
With these first folds effected, the suction means are traversed further to a revolver, or revolving head, provided with radial grippers by which the die-cuts are taken up.
The circumference of the revolver is fitted with fixed and/or movable folding means operating in conjunction with support means, generally capable of movement between two limit positions, by which the securing flap and the endmost side panel are turned in toward the center of the die-cut, thereby completing the tube.
It will be observed that, with machines of the type in question, removal of the die-cut from the bottom of the stack is brought about by discrete movements first in one direction, whereby the die-cut is picked up and transferred to a successive station, then in the opposite direction, in order to return to an at-rest condition in which the suction means are repositioned in contact with the next die-cut, at the bottom of the stack. Thus, given that the transfer trajectory of the die-cuts is intercepted by the suction means, there can be no movement of each successive die-cut until the suction means have been returned to the at-rest position.
Clearly enough, such an arrangement involves long operating times, low productivity and considerable noise, as well as imposing limits on the maximum traverse speeds of the various components invested with reciprocating movement.
Accordingly, the object of the invention is to provide an automatic machine capable of operating continuously, hence of overcoming these drawbacks.